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	<head>
		<title>three.js webgl - sprites</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
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	<body>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - sprites
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			let camera, scene, renderer;
			let cameraOrtho, sceneOrtho;

			let spriteTL, spriteTR, spriteBL, spriteBR, spriteC;

			let mapC;

			let group;

			init();

			function init() {

				const width = window.innerWidth;
				const height = window.innerHeight;

				camera = new THREE.PerspectiveCamera( 60, width / height, 1, 2100 );
				camera.position.z = 1500;

				cameraOrtho = new THREE.OrthographicCamera( - width / 2, width / 2, height / 2, - height / 2, 1, 10 );
				cameraOrtho.position.z = 10;

				scene = new THREE.Scene();
				scene.fog = new THREE.Fog( 0x000000, 1500, 2100 );

				sceneOrtho = new THREE.Scene();

				// create sprites

				const amount = 200;
				const radius = 500;

				const textureLoader = new THREE.TextureLoader();

				textureLoader.load( 'textures/sprite0.png', createHUDSprites );
				const mapB = textureLoader.load( 'textures/sprite1.png' );
				mapC = textureLoader.load( 'textures/sprite2.png' );

				mapB.colorSpace = THREE.SRGBColorSpace;
				mapC.colorSpace = THREE.SRGBColorSpace;

				group = new THREE.Group();

				const materialC = new THREE.SpriteMaterial( { map: mapC, color: 0xffffff, fog: true } );
				const materialB = new THREE.SpriteMaterial( { map: mapB, color: 0xffffff, fog: true } );

				for ( let a = 0; a < amount; a ++ ) {

					const x = Math.random() - 0.5;
					const y = Math.random() - 0.5;
					const z = Math.random() - 0.5;

					let material;

					if ( z < 0 ) {

						material = materialB.clone();

					} else {

						material = materialC.clone();
						material.color.setHSL( 0.5 * Math.random(), 0.75, 0.5 );
						material.map.offset.set( - 0.5, - 0.5 );
						material.map.repeat.set( 2, 2 );

					}

					const sprite = new THREE.Sprite( material );

					sprite.position.set( x, y, z );
					sprite.position.normalize();
					sprite.position.multiplyScalar( radius );

					group.add( sprite );

				}

				scene.add( group );

				// renderer

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				renderer.autoClear = false; // To allow render overlay on top of sprited sphere

				document.body.appendChild( renderer.domElement );

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function createHUDSprites( texture ) {

				texture.colorSpace = THREE.SRGBColorSpace;

				const material = new THREE.SpriteMaterial( { map: texture } );

				const width = material.map.image.width;
				const height = material.map.image.height;

				spriteTL = new THREE.Sprite( material );
				spriteTL.center.set( 0.0, 1.0 );
				spriteTL.scale.set( width, height, 1 );
				sceneOrtho.add( spriteTL );

				spriteTR = new THREE.Sprite( material );
				spriteTR.center.set( 1.0, 1.0 );
				spriteTR.scale.set( width, height, 1 );
				sceneOrtho.add( spriteTR );

				spriteBL = new THREE.Sprite( material );
				spriteBL.center.set( 0.0, 0.0 );
				spriteBL.scale.set( width, height, 1 );
				sceneOrtho.add( spriteBL );

				spriteBR = new THREE.Sprite( material );
				spriteBR.center.set( 1.0, 0.0 );
				spriteBR.scale.set( width, height, 1 );
				sceneOrtho.add( spriteBR );

				spriteC = new THREE.Sprite( material );
				spriteC.center.set( 0.5, 0.5 );
				spriteC.scale.set( width, height, 1 );
				sceneOrtho.add( spriteC );

				updateHUDSprites();

			}

			function updateHUDSprites() {

				const width = window.innerWidth / 2;
				const height = window.innerHeight / 2;

				spriteTL.position.set( - width, height, 1 ); // top left
				spriteTR.position.set( width, height, 1 ); // top right
				spriteBL.position.set( - width, - height, 1 ); // bottom left
				spriteBR.position.set( width, - height, 1 ); // bottom right
				spriteC.position.set( 0, 0, 1 ); // center

			}

			function onWindowResize() {

				const width = window.innerWidth;
				const height = window.innerHeight;

				camera.aspect = width / height;
				camera.updateProjectionMatrix();

				cameraOrtho.left = - width / 2;
				cameraOrtho.right = width / 2;
				cameraOrtho.top = height / 2;
				cameraOrtho.bottom = - height / 2;
				cameraOrtho.updateProjectionMatrix();

				updateHUDSprites();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				const time = Date.now() / 1000;

				for ( let i = 0, l = group.children.length; i < l; i ++ ) {

					const sprite = group.children[ i ];
					const material = sprite.material;
					const scale = Math.sin( time + sprite.position.x * 0.01 ) * 0.3 + 1.0;

					let imageWidth = 1;
					let imageHeight = 1;

					if ( material.map && material.map.image && material.map.image.width ) {

						imageWidth = material.map.image.width;
						imageHeight = material.map.image.height;

					}

					sprite.material.rotation += 0.1 * ( i / l );
					sprite.scale.set( scale * imageWidth, scale * imageHeight, 1.0 );

					if ( material.map !== mapC ) {

						material.opacity = Math.sin( time + sprite.position.x * 0.01 ) * 0.4 + 0.6;

					}

				}

				group.rotation.x = time * 0.5;
				group.rotation.y = time * 0.75;
				group.rotation.z = time * 1.0;

				renderer.clear();
				renderer.render( scene, camera );
				renderer.clearDepth();
				renderer.render( sceneOrtho, cameraOrtho );

			}

		</script>
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